The invention relates to a tool for the injection molding of toothbrush bodies consisting of two different, plastic components that are injection molded consecutively.
A tool for the injection molding of toothbrush bodies consisting of two consecutively injection molded plastic components is known from EP 0,678,368 A1. It comprises two mold parts that can be moved relative to each other and that together form several groups of parallel mold cavities. For each group of mold cavities, one of the mold parts has a recess into which a mold insert can be inserted. The mold inserts have partial cavities that correspond to the head area of the toothbrush bodies. The first plastic component is injected into two of the total of four groups of mold cavities while the second plastic component is injected into the two remaining groups. After the injection of the first plastic component, the mold inserts are lifted out of the mold cavities with the adhering blanks and placed into the mold cavities of the other group pair for purposes of injecting the second plastic component.
The mold inserts are arranged along the circumference of a circular rotary disk by means of which the mold inserts can be moved between the groups of the mold cavities. This results in a configuration of the mold cavities that generally faces radially away from the mid-point of the rotary disk. An unused surface area is left on the mold parts between the groups of mold cavities.
Through the invention, a considerably more compact arrangement of the groups of mold cavities is achieved.
According to a first aspect of the invention, the mold cavities of each group pair are arranged parallel to each other and to the mold cavities of the other group pair. One group of each group pair of mold cavities is offset with respect to the other group, perpendicular to the lengthwise direction of the mold cavities. The head ends of the mold cavities of one group of each group pair are oriented so as to face each other. As a result of this arrangement of the groups of mold cavities, the available surface area of the preferably rectangular or square mold parts is optimally utilized. The groups of mold cavities can be arranged closely adjacent to the mold parts. The groups of mold cavities, relative to a rectangle that surrounds them, are preferably arranged diagonally across from each other, whereby in each case, two groups of mold cavities diagonally across from each other constitute one group pair whose mold cavities are oriented parallel to each other but in the opposite direction. The head areas of the mold cavities of each group pair are in a row or in two adjacent rows so that the corresponding mold inserts can be mounted on a shared carrier that is lifted and rotated by 90xc2x0 in order to transfer the blanks that have been injected with the first plastic component from the first group pair of mold cavities into the mold cavities of the second group pair.
According to a second aspect of the invention, the lengthwise direction of the mold cavities is oriented tangentially to an orbit along which the mold inserts are moved during the transfer from one group of mold cavities to another. This embodiment is especially advantageous if the brush bodies are injection molded from more than two plastic components.